Chapter I: Part 1

The _ATOM_ and the _OCEAN_

by E. W. Seabrook Hull

U.S. ATOMIC ENERGY COMMISSION
Division of Technical Information
_Understanding the Atom Series_

The Understanding the Atom Series

Nuclear energy is playing a vital role in the life of every man, woman, and child in the United States today. In the years ahead it will affect increasingly all the peoples of the earth. It is essential that all Americans gain an understanding of this vital force if they are to discharge thoughtfully their responsibilities as citizens and if they are to realize fully the myriad benefits that nuclear energy offers them.

The United States Atomic Energy Commission provides this booklet to help you achieve such understanding.

{Edward J. Brunenkant}
Edward J. Brunenkant, Director
Division of Technical Information

UNITED STATES ATOMIC ENERGY COMMISSION

Dr. Glenn T. Seaborg, Chairman
James T. Ramey
Wilfrid E. Johnson
Dr. Theos J. Thompson
Dr. Clarence E. Larson

The _ATOM_ and the _OCEAN_

by E. W. Seabrook Hull

CONTENTS

SEEKING ANSWERS 1
Energy for Exploration 3
THE WORLD OCEAN 6
Ocean Movements 7
A Mix of Elements 10
The Sea’s Interfaces 11
The Sea’s Resources 11
NUCLEAR ENERGY’S ROLE 13
Radionuclides in the Sea 13
Research Projects 23
Oceanographic Instruments 35
Environmental Safety Studies 41
The Atom at Work in the Sea 42
Ocean Engineering 51
Fresh Water from Seawater 52
Radiation Preservation of Seafood 54
Project Plowshare 56
A New _Fram_ 56
THE THREE-DIMENSIONAL OCEAN 57
SUGGESTED REFERENCES 58

United States Atomic Energy Commission
Division of Technical Information
Library of Congress Catalog Card Number: 67-62476
1968

The _ATOM_ and the _OCEAN_

By E. W. SEABROOK HULL

SEEKING ANSWERS

Historians of the future will record that man almost simultaneously unlocked the secret of atomic energy and ventured into new domains beneath the closed doors of the world ocean, in one of the greatest exploration endeavors of all time.

History may also show how these two efforts to benefit mankind became closely interthreaded—how nuclear energy, in its many forms and applications, played a major role in the efforts to explore and exploit “the other three-quarters” of our planet, and moreover, how the very development of a nuclear technology enforced our need to know more about the sea around us.

Nuclear energy is a fundamental physical phenomenon, like the actions of the wheel, the lever, or the inclined plane. Like chemical combustion or electricity, it is but another means for men to do useful work, whether that work be in the interests of science, commerce, recreation, or war. To this extent, nuclear energy is universal, as applicable in the sea as it is on land or in outer space. Wherever man goes and whatever he does, he requires energy to get him there and energy for his work or play when he arrives. Some of the places he now seeks to pioneer are hard to investigate by anyone encumbered with bulky traditional energy sources—coal, fuel oil, or storage batteries. The ocean in its full three-dimensional scope is one of these places.

The atom is the most concentrated source of energy, and one of the most diverse. Thus, not only are we able to do familiar things better with nuclear energy (the nuclear-powered submarine is a dramatic example), but we are also able to do things never before possible (such as studying the diffusion of dissolved salts in the open ocean or extending the useful life of seafoods through irradiation).

Nuclear energy has at last enabled us to realize the predictions of Jules Verne’s adventure tale, _Twenty Thousand Leagues Under the Sea_, and to build a true submarine—a craft whose submerged existence is limited only by the physiological and psychological endurance of its human crew. This fact in itself has added greatly to our need to learn much more about the ocean, for the sea is an opaque and strange environment in which the deadly game of hunt-and-be-hunted will be won by whoever knows the ocean best.

The very fact that we have nuclear energy means we have nuclear wastes; many of these inevitably find their way into the ocean, as all things do. We need to know more about the watery world before we can safely allow this inflow to continue.

In the waters of the seven seas are enough deuterium and tritium to power tomorrow’s thermonuclear power plants[1] for millions of years. These rare, heavy varieties of hydrogen, enormously abundant in the vastness of the sea, comprise an energy source without limit for all nations, which need only develop the technological ability to extract them and put them to work.

Energy for Exploration

For this exploration, men need to put instruments, navigation beacons (see figures on pages 46 and 47), and other devices on the deep ocean floor, where they must operate for long periods of time unattended and with no external source of power. Radioisotope-powered generators, capitalizing on the energy of disintegrating radioactive atoms, are almost the only devices capable of fulfilling these requirements.[2] Man also wants to do productive work under the ocean, such as drilling seafloor oil wells, mining, and salvaging for profit some of the tens of thousands of cargoes lost at sea during thousands of years of ocean commerce. Eventually, he even wants to farm the ocean floor.

All these activities require energy—energy in an environment where most sources cannot be applied. Above all, man wants to go down himself to explore, to work, and perhaps to direct nuclear-powered robots to do even more work. This means that small, manned, nonmilitary submersibles will be needed—vessels whose endurance should not be limited by the short life of traditional power sources, but should draw on the fissioning atomic nucleus, harnessed in small reactors.[3]

To work effectively in any environment, we must first know and understand it. This is the job of science. In the quest for knowledge and understanding of the ocean, nuclear energy provides scientists with better instruments to put down into the depths and wholly new techniques for the direct study of the many oceanic processes.

For example, take the role of radioisotope tracers: For the first time, these telltale atoms permit us to study the metabolism of tiny plankters, the often microscopic drifting creatures of the sea that in their incredible abundance form the base of the entire marine food chain, including fish eaten by humans. Even fallout isotopes from nuclear tests enable us to trace important physical oceanographic events, such as the ponderous process known as overturning, which transports oxygen-rich surface water to the deeps and nutrient-rich bottom water to the surface. Radioisotope tracers also provide a tool for studying the mechanics of littoral transport, which continually tears down some beaches and builds up others. They also enable us to determine if oceanic processes are likely to concentrate fallout particles and deliver them in dangerous doses through the food chain to our dinner tables.[4]

By using other nuclear energy technology, we are better able to ascertain the age and composition of deep ocean sediments and the rate at which they are deposited, how a tsunami (tidal wave) propagates across vast distances, how tides operate in the open ocean, where the brown shrimp of the Carolina coast go every fall, and the migration patterns of tuna, swordfish, and other valuable food fish.

These are just a few of the answers we seek from the world ocean—answers important for more productive fisheries, more accurate long-range weather forecasting, possible control of hurricanes and typhoons, pollution control, safer and more economical shipping, better recreation, and numerous other matters that bear on our health, well-being, and day-to-day lives.

On all these endeavors the ocean exerts a major influence. And in each, atomic energy is helping assemble and interpret answers.

THE WORLD OCEAN

But what of this environment into which, armed with the atom, we plunge with such enthusiasm and expectations? A portrait is in order, which must be brief, for not all the books ever written about the sea have yet described it fully.

The world ocean covers 70.8% of our planet. It contains 324,000,000 cubic miles of seawater. Living in it are upwards of a million different species of plants and animals. They range from one-celled organisms that can only be seen with a microscope to the largest creature ever to have lived on this earth—the giant blue (or sulfur-bottom) whale, captured specimens of which have exceeded 90 feet in length and 100 tons in weight.

The ocean’s depth ranges from 600 feet or less above continental shelves to more than 35,000 feet at the Marianas Trench. The mean depth is 12,451 feet. Sea bottom topography includes wide plains, the world’s longest mountain range, steeply rising individual truncated peaks called _guyots_ (pronounced gee-ohs), gentle slopes, narrow canyons, and precipitous escarpments. Mountains higher than Everest rise from the ocean floor and never pierce the surface.

Ocean Movements

The ocean is constantly in motion—not just in the waves and tides that characterize its surface but in great currents that swirl between continents, moving (among other things) great quantities of heat from one part of the world to another. Beneath these surface currents are others, deeply hidden, that flow as often as not in an entirely different direction from the surface course.

These enormous “rivers”—quite unconstant, sometimes shifting, often branching and eddying in a manner that defies explanation and prediction—occasionally create disastrous results. One example is El Niño, the periodic catastrophe that plagues the west coast of South America. This coast normally is caressed by the cold, rich Humboldt Current. Usually the Humboldt hugs the shore and extends 200 to 300 miles out to sea. It is rich in life. It fosters the largest commercial fishery in the world and is the home of one of the mightiest game fish on record, the black marlin. The droppings of marine birds that feed from its waters are responsible for the fertilizer (guano) exports that undergird the Chilean, Peruvian, and Ecuadorian economies.

Every few years, however, the Humboldt disappears. It moves out from shore or simply sinks, and a flow of warm, exhausted surface water known as El Niño takes its place. Simultaneously, torrential rains assault the coast. Fishes and birds die by the millions. Commercial fisheries are closed. The beaches reek with death. El Niño is a stark demonstration of man’s dependence on the sea and why he must learn more about it.

There are other motions in the restless sea. The water masses are constantly “turning over” in a cycle that may take hundreds of years, yet is essential to bring oxygen down to the creatures of the deeps, and nutrients (fertilizers) up from the sea floor to the surface. Here the floating phytoplankton (the plants of the sea) build through photosynthesis the organic material that will start the nutrient cycle all over again. Enormous tonnages of these tiny sea plants, rather than being rooted in the soil, are separated from solid earth by up to several vertical miles of saltwater. Sometimes, too, there is a more rapid surge of deep water to the surface, a process known as upwelling.

Internal waves, far below the surface, develop between water masses that have different densities and between which there is relative motion. These waves are much like the wind-driven waves on the surface, though much bigger: Internal waves may have heights of 300 feet or more and be 6 miles or more in length!

Among other motions of the sea there are landslides, or turbidity currents, which are great boiling mixes of mud, rock, sand, and water rushing down submarine mountainsides at speeds of a mile a minute. They destroy everything in their paths and spread clouds of debris over the abyssal plains like a sandstorm, producing fanlike deposits radiating far out from the base of the slope. And there are tsunamis, or seismic sea waves—popularly misnamed “tidal waves”—that transmit energy from undersea earthquakes or volcanic eruptions. At sea, these waves are only a few inches high, but they may travel great distances at 500 miles an hour. As they approach the shoaling waters of a coast, they are slowed to about 30 miles an hour and build up great surface waves capable of destroying harbor and coastal installations.

A Mix of Elements

The sea is a chemistry, too. Over 60 elements have been discovered in measurable amounts in solution or in suspension in the ocean. Many of these are in the form of salts, making seawater a highly efficient electrolyte, and a most corrosive fluid. The study of corrosion and techniques for combatting it is a continuous one in which nuclear energy already has a principal role.

Because the sea is so much a chemistry, it is a potential source of minerals for the world’s growing industrial appetite. All of our magnesium and most of our bromine already are extracted directly from seawater. Oil and sulfur are mined from the sea floor or beneath it, as are coal (United Kingdom and Japan), iron ore (Japan), tin (Thailand and United Kingdom), diamonds (Southwest Africa), and gold (Alaska). In the layered sediments that cover the ocean-basin floors to depths of thousands of feet, geologists believe there also may be found some missing chapters of earth history.

The ocean, by and large, is an opaque fluid through which light travels only a few hundred feet and most other radiant energy not much more than a few yards; yet through this same fluid, sound waves, by contrast, have been transmitted and received over distances of many thousand miles.

The Sea’s Interfaces

What of the interfaces of the sea? Above three-quarters of the globe, water and air are in constant contact, continually exchanging heat and moisture. This is a major factor in the making of weather and climate. The sea constantly feeds electricity into the atmosphere, primarily through the electron-scrubbing action of tiny popping bubbles at the sea surface. It also lifts tiny crystals of salt and the remains of microscopic sea creatures into the air. Perhaps these are the nuclei on which moisture condenses to trigger hurricanes, since it is the latent heat of vaporization of air, made over-moist by long travel over the tropical sea, that provides a hurricane’s energy.

Along its land edges, the sea is constantly working on the shore—sometimes gently, sometimes violently—breaking down rock cliffs, opening bays and harbors, closing channels and inlets, smashing breakwaters and seawalls, and moving sand up and down and to and from beaches.

The Sea’s Resources

In summary, then, the ocean, the largest single geographical feature of our planet, is infinitely varied and infinitely complex. We are learning it bears on our day-to-day living in ways we never suspected. It is the largest resource of food for our exploding population, the largest resource of minerals with which to support the world’s burgeoning industries, the largest resource of energy, and, of course, it is the largest supply of water. It is mankind’s largest dumping ground for the wastes of cities and industries. It is the source of much pleasure and recreation.

Men already have lived experimentally for weeks at a time on the bottom of the ocean. Both sea floor laboratories and military bases are being planned or, in a few cases, installed. Sea floor mining complexes are in the conceptual design stage. It is only a matter of time before recreational “aquotels” are built safely below the sea’s restless surface. Private sports submarines are an actual, though costly, reality. It is not inconceivable that in the not-too-distant future human beings may overflow the land into complete, self-sufficient communities below the oceans.

NUCLEAR ENERGY’S ROLE

The role of nuclear energy in the study, exploration, and utilization of the world ocean is best defined by citing the specific oceanographic interests of the U. S. Atomic Energy Commission (AEC): Development of better instruments and devices for work and study in the ocean, development of ever-stronger national sea power, conversion of seawater to fresh water, possible modification of ocean boundaries, purely scientific studies to advance knowledge, and, indirectly at least, improving the state of oceanographic engineering. Among the technological products of the nuclear age are radionuclides, neutron sources and other radiation sources, radioisotope heat and electric generators, and nuclear reactors. All these are applied to ocean-related endeavors.

Several divisions of the AEC have important oceanic interests. These range from pure oceanographic research to development of specific instruments, nuclear reactors, radioisotopic power sources, and other devices for use in or under the ocean. The AEC also conducts extensive marine environmental studies to monitor the effects or ensure the safety of specific projects involving nuclear energy. A statistical summary of specific AEC programs in oceanography is shown in Table I on page 14.

Radionuclides in the Sea

Before we can follow the atom down into the sea, we must understand something about the potentials, both good and bad, of this incursion of one of our most advanced technologies into one of earth’s least understood environments. This adventurous probing has ramifications for studying both man-produced radioactivity in the sea and the ocean itself as an uncontaminated environment.

TABLE I
AEC OCEANOGRAPHY PROGRAM 1968
Expenditures
Estimate
_Research Activities_

Division of Biology and Medicine $4,000,000
Studies of uptake, concentration, distribution and
effects of radioisotopes on marine life, of
geochemical cycling of elements, and of geophysical
diffusion and transport.
Division of Research 25,000
Geological dating of corals and other marine and
terrestrial materials.
Division of Isotopes Development 190,000
Radioisotope applications to devices for marine
systems, such as current meters, analysis and
recovery of sedimentary minerals, and underwater
sound transmission.
Division of Reactor Development and Technology 197,000
Studies of factors affecting dissolution and
dispersal of accidentally released radionuclides, and
site evaluations.
Division of Space Nuclear Systems 275,000
Nuclear power sources for aerospace applications.
Division of Military Applications 850,000
Ocean environmental observation and prediction.
_Total—Research Activities_ 5,537,000

_Engineering Activities_

Division of Reactor Development and Technology 5,900,000
Radioisotope and reactor power development.
Division of Naval Reactors 1,320,000
Deep submergence research vehicle.
_Total —Engineering Activities_ 7,220,000
_Total—ABC Oceanographic Activities_ 12,757,000

Radionuclides (radioactive atoms) can find their way into the sea from natural radiation sources or from nuclear energy operations undertaken by the United States and other countries since 1945. Specific man-made sources in the past may have included nuclear weapons tested in the atmosphere and under water, the cooling water and wastes of nuclear reactors, laboratories and nuclear-powered ships, containers of radioactive waste disposed of at sea[5], radioisotope energy devices, and intentional injection of radioisotope tracers for scientific research. In the future, they may also include reentry from space of upper-stage nuclear rockets or satellite-borne nuclear energy sources.

In order to evaluate the effects of these materials in the ocean environment, it is necessary to know many things. Just how much radiation is introduced? In what form? Where geographically? How are these radionuclides dispersed or concentrated physically, chemically, biologically, and geologically? What is the net result in each case now, and what will it be many years hence?

These questions are not answered easily. There is, as yet, no satisfactory laboratory substitute for the open ocean. Research for the most part must be conducted at sea, where tests and measurements are difficult at best, and where results therefore are often suspect. Further, if we are to study the effects of man-induced changes in a natural environment, it would have been advantageous to have known the nature of that environment before the changes were introduced—which, by and large, in the case of the ocean we do not. So we must start with a contaminated environment and try to separate what we have put there ourselves from what would have been there anyway. It isn’t an easy task to make the physical and biological observations that will make this distinction.

Table II CONCENTRATION AND AMOUNTS OF 42 OF THE ELEMENTS IN SEAWATER
Element Concentration Amount of element in Total amount in
(mg/l) seawater (tons mile³) the oceans (tons)

Chlorine 19,000.0 89.5 × 10⁶ 29.3 × 10¹⁵
Sodium 10,500.0 49.5 x-10⁶ 16.3 × 10¹⁵
Magnesium 1,350.0 6.4 × 10⁶ 2.1 × 10¹⁵
Sulphur 885.0 4.2 × 10⁶ 1.4 × 10¹⁵
Calcium 400.0 1.9 × 10⁶ 0.6 × 10¹⁵
Potassium 380.0 1.8 × 10⁶ 0.6 × 10¹⁵
Bromine 65.0 306,000 0.1 × 10¹⁵
Carbon 28.0 132,000 0.04 × 10¹⁵
Strontium 8.0 38,000 12,000 × 10⁹
Boron 4.6 23,000 7,100 × 10⁹
Silicon 3.0 14,000 4,700 × 10⁹
Lithium 0.17 800 260 × 10⁹
Rubidium 0.12 570 190 × 10⁹
Phosphorus 0.07 330 110 × 10⁹
Iodine 0.06 280 93 × 10⁹
Barium 0.03 140 47 × 10⁹
Indium 0.02 94 31 × 10⁹
Zinc 0.01 47 16 × 10⁹
Iron 0.01 47 16 × 10⁹
Aluminum 0.01 47 16 × 10⁹
Molybdenum 0.01 47 16 × 10⁹
Selenium 0.004 19 6 × 10⁹
Tin 0.003 14 5 × 10⁹
Copper 0.003 14 5 × 10⁹
Arsenic 0.003 14 5 × 10⁹
Uranium 0.003 14 5 × 10⁹
Nickel 0.002 9 3 × 10⁹
Vanadium 0.002 9 3 × 10⁹
Manganese 0.002 9 3 × 10⁹
Antimony 0.0005 2 0.8 × 10⁹
Cobalt 0.0005 2 0.8 × 10⁹
Caesium 0.0005 2 0.8 × 10⁹
Cerium 0.0004 2 0.6 × 10⁹
Silver 0.0003 1 5 × 10⁸
Cadmium 0.0001 0.5 150 × 10⁶
Tungsten 0.0001 0.5 150 × 10⁶
Chromium 0.00005 0.2 78 × 10⁶
Thorium 0.00005 0.2 78 × 10⁶
Lead 0.00003 0.1 46 × 10⁶
Mercury 0.00003 0.1 46 × 10⁶
Gold 0.000004 0.02 6 × 10⁶
Radium 1 × 10⁻¹⁰ 5 × 10⁻⁷ 150

Adapted from _The Mineral Resources of the Sea_, by John L. Mero,
American Elsevier Publishing Company, New York, 1964.

Many sea creatures are efficient, selective concentrators of “trace elements”, which occur in seawater only in minute portions. These elements are difficult enough to detect qualitatively and all but impossible to analyze quantitatively. Yet among the elements the sea’s plants and animals concentrate are the very materials with which we are apt to be most concerned: Strontium, cesium, cerium, ruthenium, cobalt, iodine, phosphorus, zinc, manganese, iron, chromium, and others. Radioisotopes[6] of all these elements occur as by-products of human nuclear activities. Many concentrating organisms are microscopic in size and are frequently impossible to raise in captivity. It is apparent that we are faced with a research program of considerable challenge and proportion.

We need to know _how_ each marine species concentrates. Is it from the food it eats, by absorption from the water, or both? Does it concentrate an element by continuous accumulation, or is there a constant turnover of the material in the organism’s system? (In the first case, once the creature became radioactive it would remain so throughout its life or until the radioactivity decayed. In the second case, however, the radioactivity might be a transient condition, assuming the creature could find its way into uncontaminated water and were able to flush itself.) Obviously, both the cycling time of the radioisotope in the organism and its radioactive half-life[7] must be taken into account.

Even if we should manage to identify all the marine concentrators and gain some insight into their metabolic processes, this would be only a first step. For example, one tiny form of planktonic protozoan, _acantharia_, concentrates up to 15% of its own weight of strontium, including the radioisotope strontium-90. It is eaten by larger zooplankton (animals), such as copepods, which are eaten by little fish, which, in turn, are eaten by bigger fish, etc. Somewhere along this food chain, perhaps, a fish will come along that is favored for human dinner tables. How much strontium-90 has _that_ fish accumulated through swallowing its prey and by absorption from the water? Is the radioactivity in its scales, bones, viscera, and other usually uneaten portions, or in its flesh?

It is probable, though as yet by no means proven, that among the million or so oceanic species of plant and animal life, there are concentrators of virtually all the 60 or more elements found in seawater. To identify and study them is an enormous undertaking, which is often possible only by using radioisotopes as tools.

And what of the immediate and genetic effects of radiation on each species? Studies of reef fish in the nuclear testing area in the Marshall Islands have shown that radioiodine in the water caused thyroid gland damage long after the amount of radioiodine remaining in the water was too low to be detected. Studies of salmon in the Columbia River have shown some physiological variations between those fish whose eggs and young were reared in radioactive waters and those that were not, though these variations have not been determined to be statistically significant or different from variations caused by other contaminants.

Studies are being made of the reproductive efficiency and patterns of sea creatures in a radiation-contaminated environment, compared with those in an uncontaminated environment, to learn such things as the numbers, survival rates, and sex ratios of the offspring, and any genetic abnormalities or mutations. Many more studies are needed. Always, the task is made difficult by insufficient detailed knowledge of the original natural environment, the limitations of laboratory experiments, and the mechanics of trying to follow the reproductive cycles of free-floating or swimming organisms in any statistically meaningful manner through successive generations.

One obviously important kind of research deals with the rate, pattern, and means by which radionuclides are distributed into the sea from a point source, such as the mouth of a river or a nuclear test site. Transport and diffusion of radioactivity can be, and are, influenced by physical, chemical, biological, or geological means, separately or all at once. This has led the AEC to support scientific studies of currents, upwelling, downwelling, convergence, diffusion, mixing rates, air-sea interactions, chemical and geological processes in the sea, and the horizontal and vertical migrations of sea life.

In much of the ocean there is an acoustic “floor”, known as the _deep scattering layer_ (because of what it does to sound waves), which is believed to consist primarily of zooplankton. Every 24 hours the layer migrates up and down through several hundred feet of water. At night the countless small animals graze in the rich sea-plant pastures near the surface; during daylight, back at the lower level, they undoubtedly are heavily fed upon by larger animals. Over a period of time, the layer accounts for considerable vertical transport of materials. (See figure above.) Other life forms may move materials still farther down, or, in some instances, back up—as when the sperm whale descends to the depths to fight and best a giant squid, and then returns to the surface to eat it.

Constantly drifting downward is a great volume of material—the dead bodies, skeletons, excrement, and other waste from sea life at all depths. As it sinks there is a constant exchange of matter between it and the surrounding water through chemical, physical, and biological processes. Eventually, the molecules of material added to the bottom sediments may be returned to the water mass by bacteriological action or the eating and living habits of sea floor animals.

Biological transport works in other ways, too. Most pelagic (free-swimming) fish are great travelers. They account for a tremendous movement of material, namely themselves, from one place to another. Tuna, swordfish, whales, porpoises, and sea birds may travel thousands of miles in a single year. Such migrations may serve, variously, as mechanisms for either dispersal or concentration of elements or nutrients. The anadromous (river-ascending) fishes, such as salmon, herring, sturgeon, and shad, concentrate in freshwater streams in untold numbers to spawn. After hatching, the young seek the ocean and scatter widely until they, too, feel the urge to return to the rivers and lakes whence they came, to spawn and die there as did their ancestors.

Ocean currents may transport concentrations of radionuclides essentially undiluted for thousands of miles. Surface currents move at speeds of up to five knots (nautical miles per hour). Normally current waters do not mix readily with the water mass through which they pass. Because of the slowness of vertical circulation in the ocean, radionuclides deposited on the surface of the ocean may take a thousand years to reach the bottom. But the vertical transport sometimes is much more rapid: When the wind piles too much water against a coastline, the resultant downwelling (sinking) may move radionuclides suddenly into the deeper ocean. Or, conversely, when the wind and the rotation of the earth combine to force the surface water _away_ from the coast, deep water may suddenly rise to replace it, a process known as upwelling.

Light energy
Dissolved gases
Birds and man
Rivers and ice
Wave action
Surface mixed layer 20-100m
Suspended matter
Elements in true solution
Plants phytoplankton
Animals
Deep water
Elements in true solution in deep water
Buried in sediment
Physical Processes
_Transport by wind_
_Transport by current_
_Turbulent mixing_
_Sedimentation_
_Transport_ by animals
_Volcanic action_
_Diffusion_
Chemical or Biological Processes
_Photosynthesis_
_Dissolving_
_Upwelling_
_Decomposition and respiration_
_Sorption_ by sediment surface
_Redissolving_ from sediment
_Chemical precipitation_
Combined Processes
_Sedimentation and decomposition_ by bacteria
_Scavenging_

Some recent evidence indicates that the passage of a hurricane across the ocean drives surface water out from the storm center in all directions. This, too, produces upwelling. If radionuclides fall on the Arctic ice pack or on the Greenland or Antarctic ice caps, it may be years before they are released to the sea. In more or less stable conditions at sea, radionuclides may remain trapped above the thermocline (a layer of sharp temperature change usually less than 100 meters below the surface) for a considerable period. Then a severe storm may destroy the thermocline and mix the waters to much greater depths. The process of diffusion in the ocean is not well understood, due both to the difficulty of the measurements that have to be made and to the variety of other factors affecting both vertical and horizontal transport of materials. Here again, however, the existence of radionuclides, introduced artificially at a known time and place, is materially aiding these investigations by making a particular water mass detectable and traceable.

In chemical oceanography, the AEC is concerned with the fact that in some instances our society is introducing elements, ions, and compounds that have not been naturally found in the sea, as well as natural materials in greater concentration than is normal. These may combine with other materials in the sea, changing into new forms or substances, or removing them from solution entirely. Any change in the chemical composition of the ocean is quite likely to have biological effects, some of which may prove detrimental to man.

A disturbance of the chemical balance of the sea is thought to be responsible, at least in part, for the periodic, disastrous plankton “blooms” known as “red tides”. Such a sudden, explosive overpopulation of plankton is a natural phenomenon, but one that can be triggered by man-made pollution. When it occurs, plankton multiply so rapidly that the oxygen in the water is depleted and many fish die from suffocation.

Fortunately, nuclear energy operations account for an extremely small portion of the chemical contamination of the sea, when contrasted with the tremendous volume of poisons dumped daily into it in the form of other industrial and municipal waste and agricultural pesticides.

Research Projects

The AEC supports oceanographic research conducted by its own laboratories and by other federal agencies, as well as by non-government research scientists. The Environmental Sciences Branch of the Division of Biology and Medicine has begun the long and complex task of unraveling the mystery of the fate of radionuclides in the ocean. Valuable techniques have been developed for the intentional injection of radioisotopes into the sea for specific research. Scientists are now able to conduct investigations that were never before possible. In some instances, traditional scientific concepts and theories have been shattered, or at least severely shaken, by new evidence gathered by radioisotope techniques.

Since 70% of the earth’s surface is water, at least 70% of the radioactive debris lofted into the stratosphere during atmospheric nuclear weapons tests falls into the ocean. An additional small proportion finds its way into the sea as the run-off from the land. In the case of tests at sea, the majority of radiation immediately falls into the water nearby. For this reason, the ocean around the sites in the Marshall Islands where U. S. tests were conducted has provided a unique opportunity to study the effect of large concentrations of radionuclides. Particularly significant studies have been conducted of the absorption of radionuclides by plants and animals living on nearby reefs and islands, and of both lateral and vertical diffusion rates of elements in the open ocean.[8]

The 1954 nuclear test at Eniwetok Atoll produced heavier-than-expected local radioactive fallout. Since then, both American and Japanese scientists have studied water-mass movement rates, using the fallout radionuclides strontium-90 and cesium-137 themselves as tracer elements. These nuclides produced in the test have been detected at depths down to 7000 meters in the far northwestern Pacific in the vicinity of Japan.

If this results from simple eddy diffusion, as some scientists believe, it is a case of diffusion at a very high rate. Other scientists suggest that other factors may have contributed to the vertical transport of the radionuclides to these depths. Still others believe that the strontium-90 and cesium-137 might not have originated with the U. S. Pacific tests at all, but rather with Russian tests in the Arctic taking place at about the same time. They propose the theory that a syphoning effect in the Bering Strait causes a current to flow out of the Arctic Ocean and down under the surface waters of the western Pacific. In support of this, Japanese researchers cite a dissolved oxygen content where these measurements were made that is different from that of other deep water in the area. If this theory should be proved correct, it would be the first indication that such a current exists.

Similar investigations have been conducted of the variations in depth of strontium-90 concentration in the Atlantic Ocean. In February 1962, when fallout from 1961 nuclear tests was high, tests south of Greenland showed that mixing of fallout was fairly rapid through the top 800 meters of water. At greater depths a colder, saltier layer of water contained only about half as much strontium-90, confirming other evidence that interchange between water masses of different physical and chemical properties is comparatively low.

Work such as this has emphasized the difficulty in making meaningful measurements of man-made radiation in the ocean. One problem is to separate the artificially produced radiation from the natural radiation, namely that from potassium-40 (which accounts for 97% of oceanic radiation) and from the radionuclides, such as tritium, carbon-14, beryllium-7, beryllium-10, aluminum-26, and silicon-32, created in the stratosphere naturally by cosmic-ray bombardment.

Another problem is the sheer physical size of the water sample required to get any measurements at all. Up to now there has been no truly effective radiation counter that can be lowered over the side of a ship to the desired depth. It is often necessary to collect a sample of many gallons at great depths and return it to the surface without its being mixed by any of the intervening water. This is difficult at best, and only rather primitive methods have been developed. None is more than partly satisfactory. A standard system is to lower a large, collapsed polyethylene bag to the desired depth, open it, fill it, and close it again, all by remote control, and then gingerly and hopefully return it to the surface. Results do not always agree among samples taken at the same location by different methods or by different scientists. There is still no universal agreement among scientists as to the quantitative validity of any of the measurements, although as more and better data are gathered there tends to be a greater concurrence.

Recently, under an AEC contract, a detector for direct measurements of gamma radiation[9] in the deep ocean was developed for the Institute of Marine Sciences, University of Miami, by the Franklin GNO Corp. (See figure above.) This unit incorporates two of the largest plastic scintillation counters[10] ever used in the ocean—each is 16 inches in diameter by 12 inches thick. This apparatus may permit direct qualitative and quantitative measurement of radiation at great depths by techniques that will be eminently more satisfactory than water sampling. Already tests with the detector have disclosed the existence of cosmic-ray effects at much greater depths than heretofore known.

Biologists from Woods Hole Oceanographic Institution in Massachusetts for the first time have been able to measure the rate of excretion of physiologically important fallout radionuclides by several species of zooplankton—_pteropods_, _pyrasomes_, _copepods_, and _euphausids_. Radioactive zinc and iodine, it was learned, are excreted as soluble ions, while iron and manganese appear as solid particles. However, the extent to which the intake and excretion of radionuclides and the vertical migration of zooplankton contribute quantitatively to the transport of radioactivity across the thermocline (and into the ocean deeps) still can only be guessed.

Other plankton research at Woods Hole uses radioactive carbon-14 and phosphorus-32 as tracers to evaluate rates of growth and nutrient assimilation by algae (floating green plants). These investigations have revealed that the presence or absence of minute quantities of nutrient minerals in seawater affects the rate at which the algae produce oxygen by the process of photosynthesis. Since the energy of all living things—including man—is also made available by photosynthesis, and since most of the photosynthesis on earth is performed by algae afloat in the oceans, it is apparent that this research is of more than academic interest. Algae, the original energy-fixers of the “meadows of the sea”, are also the original food source for the billions of aquatic animals, and may some day prove a source of food for a mushrooming human population.

In a project with more immediate application, extensive biological and environmental studies of the Eniwetok Atoll area in the Pacific were conducted prior to the first nuclear testing there in 1948, and these studies have continued ever since. Early in the test series the Japanese, who were at first concerned with the possible contamination of their traditional marine food supplies, were invited to participate in these studies. Fisheries radiological monitoring installations were established in Japan and the U. S. (The latter was established by the AEC and administered by the U. S. Food and Drug Administration.) Neither station encountered any radiological contamination of tuna or other food fish, and the American unit has now been closed.

Groups that have cooperated with the AEC in marine radiobiological research are the University of Hawaii, University of Connecticut, Virginia Fisheries Laboratory, University of Washington, U. S. Office of Naval Research, and U. S. Bureau of Commercial Fisheries.

At the Bureau of Commercial Fisheries Radiobiological Laboratory in Beaufort, North Carolina, a cooperative effort of the AEC and the BCF is concerned with learning the effects of radioactive wastes on one of America’s most valuable marine resources—the tidal marshlands and estuaries that are essential to the continued well-being of some of our important commercial fisheries.

Table III RADIOISOTOPES THAT MIGHT BE FOUND IN AN ESTUARINE
ENVIRONMENT
Isotope Half-life

Iodine-131 8.05 days
Barium-140—Lanthanum-140 12.8 days—40 hours
Cesium-141 32.5 days
Ruthenium-103—Rhodium-103 10 days—57 minutes
Zirconium-95—Niobium-95 65 Days—35 days,
Zinc-65 245 days
Cerium-144 285 days
Manganese-54 314 days
Ruthenium-106—Rhodium-106 1 year—30 seconds
Cesium-137 30 years
Potassium-40 1.3 × 10⁹ years

(Reprinted from _Radiobiological Laboratory Annual Report_, April, 1,
1964, page 50.)

The project has determined that radionuclides are removed from waters in an estuarine environment by several physical, chemical, and biological means. For example, radionuclides are absorbed in river-bed sediments at a rate varying directly with sediment particle size. Mollusks, such as clams, marsh mussels, oysters, and scallops, not only assimilate radionuclides selectively, but do so in sufficient quantity and with sufficient reliability to be useful as indicators of the quantity of the isotopes present. Clams and mussels are indicators for cerium-144 and ruthenium-106, scallops for manganese-54, and oysters for zinc-65 (most of which winds up in the oyster’s edible portions). It was learned that scallops assimilate more radioactivity than any other mollusk. Of the total radioactivity, manganese-54 accounts for 60%: The scallop’s kidney contains 100 times as much manganese-54 as any of the other tissues and 300 times as much as the muscle, the only part of the scallop usually eaten in this country.

In a surprising unintended result, it was determined that one acre of oyster beds, comprising 300,000 individual oysters, may filter out the radionuclides from approximately 10,000 cubic meters (18 cubic miles) of water per week!

The Radiological Laboratory scientists also have found that plankton are high concentrators of both chromium-51 and zinc-65, and that zinc apparently is an essential nutrient for all marine organisms. Some plants and animals appear to reach a peak of radionuclide accumulation quickly, which then tapers off even though the radiation concentration in the water is unchanged.

While the AEC’s oceanographic research budgets have not been large, they have contributed materially to knowledge of the oceanic environment. AEC-sponsored research at Scripps Institution of Oceanography has determined by a process known as neutron activation analysis[11] that the concentration of rare earth elements in Pacific Ocean waters appears to be only about one hundredth of the level previously reported. By analysis of naturally occurring radioisotopes, they have also discovered that it takes from one million to 100 million years for lithium, potassium, barium, strontium, and similar elements introduced into the ocean from rivers to be deposited in the bottom sediments. Aluminum, iron, and titanium are deposited in from 100 to 1000 years. They have also found that sedimentation occurs in the South Pacific at a rate of from 0.3 to 0.6 millimeter per thousand years, in the North Pacific at a rate several times that figure, and in the basins on either side of the Mid-Atlantic Ridge at a rate of several millimeters per thousand years.

The University of Miami has successfully developed two methods for determining the ages of successive layers of deep ocean sediments based on the relative abundances of natural radioelements, and thereby has established a chronology of climatic changes during the last 200,000 years during which the sediments were laid down.

The U. S. is not alone in its use of nuclear energy as a tool of science. The United Kingdom has carried out radiological studies of the marine environment for many years, particularly concentrating on the effects of radionuclides from nuclear power plants on the sea immediately contiguous to the British Isles. Both the European Atomic Energy Community and the International Atomic Energy Agency also encouraged marine radiological studies. Many laboratories and government agencies in Europe, North and South America, Africa, and the Middle East and Far East have well-established and productive programs under way.

Scientists in many parts of the world have used both natural and intentionally injected radiation to study the coastwise movement of beach materials. British experimenters, for example, activate sand with scandium-46 and are thus able to follow its movement for up to four months. Pebbles (shingle) coated with barium-140 and lanthanum-140 are also used as tracers and are good for 6 weeks. Scientists at the University of California trace naturally occurring radioisotopes of thorium, which may be introduced from deposits of thorium sands along river banks. These studies are of immediate practical importance, for each year the ocean moves billions of cubic yards of sand, gravel, shingle, and rock to and from beaches and along shores. This action destroys recreational beaches, fills channels, blocks off harbors, and in general rearranges the terrain, often at considerable cost and inconvenience to mariners and other people who use the coast.

In another use of radioisotopes in marine research, studies at the AEC’s Oak Ridge National Laboratory in Tennessee have revealed radioactivity in the scales of fish taken from waters affected by the laboratory’s radioactive waste effluent. It was suggested that this phenomenon might be put to use as a tagging technique in fish-migration studies, and scientists are now working on a method using cesium-134 introduced into the fishes’ natural diet.

Some of the most extensive studies of a marine environment ever conducted are those by the AEC, the Bureau of Commercial Fisheries, and the University of Washington in the Columbia River system and the nearby Pacific Ocean. Operations at the AEC’s giant Hanford facilities some 300 miles upstream from the ocean result in the release of small amounts of radioactivity to the river and also in raising the river-water temperature. This downstream research is to determine any effects of these changes, including any that might be detrimental to man. The research encompasses studies of the variations and distributions of the freshwater “plume”—the outflow from the rivermouth—extending into the nearby Pacific, sediment analyses, studies of the population dynamics of phytoplankton, and the transport of radionuclides through the food chain.

As so often happens with basic programs, this research has produced immediate benefits. New resources of marketable oceanic fish were discovered by the scientists at depths never before fished commercially (from the edge of the continental shelf to depths of 500 fathoms and greater). Similarly, commercial quantities of one species of crab have been discovered in the deeper ocean. Other findings indicate that crab populations may have seasonal up-and-down migrations that vary according to sex. It appears, in fact, that, except while mating and as juveniles, the male and female crab populations lead separate lives. This information is important both for more efficient fisheries and for improved conservation of the crab as a food resource.

The AEC is, in short, concerned with virtually every facet of basic oceanography, and with study of the sea as a whole, for radionuclides, like their nonradioactive counterparts, can and do become involved in every phase of the vast and complex ocean ecology. In the process of pursuing its research interests, it also provides oceanographers with a whole new family of tools for study. Let us now see how atomic instruments contribute to the growing knowledge of the sea.

Oceanographic Instruments

The ocean is both a complex and a harsh environment and its study has always demanded that designers of seaworthy instruments and sampling devices be both ingenious and experienced in shipboard requirements. Until recently, these devices tended to be rugged and simple, if not indeed crude. More refined, electronic instrumentation has begun to appear in recent years, but most designs still fail to pass the test of use at sea. Even among those that do pass, there is persistent difficulty in separating desired information-carrying signals from background and system-induced “noise”. This has been a specific problem with current meters designed to be moored in the open ocean and also with one quite sophisticated gamma-ray detector.

To meet the clear need for improved devices, as well as to support its own research and increase utilization of nuclear materials and techniques, the AEC Division of Isotopes Development encourages the development of oceanographic instrumentation. This comparatively young technology already has produced exciting results. The future may be even more revealing as nuclear energy is applied more and more to the study, exploration, and exploitation of the ocean.

Instruments that have been developed under the AEC program include a current meter, a dissolved-oxygen-content analyzer, and a sediment-density meter. A new, fast method for determining the mineral content of geological samples also has been perfected.

The DEEP WATER ISOTOPIC CURRENT ANALYZER (DWICA) was developed under a contract with William H. Johnson Laboratories, Inc. It relies on radioisotope drift time over a fixed course to measure seawater flow rates ranging from 0.002 to 10.0 knots. The device embodies 12 radiation sensors spaced equally in a circle around a radioisotope-injection nozzle. Current direction can be determined to within 15 degrees. The mass of tracer isotope injected is very small—less than 10 picograms[12] per injection—and the instrument can store enough tracer material to operate for a year. The tracer can be injected automatically at intervals from 2 to 20 minutes, depending on the current. The device sits on the sea floor, where its orientation to magnetic north can be determined within 2.5 degrees.

Isotope Reservoir and equipressure system
Electric logic circuitry
Pressure protective case
Compass
Sensor ring
Flow baffle plate
Isotope injection point

A SEDIMENT DENSITY PROBE, developed under an AEC contract by Lane-Wells Company, employs gamma-ray absorption and backscatter properties[13] to determine the density of the sediments at the bottom of lakes, rivers, or the ocean, without the necessity of returning a sediment sample to the surface. It is expected that it can be modified to sense the water content of the sediments. These determinations are valuable not only for research, but also for activity that requires structures on the ocean floor, such as petroleum exploration and naval operations.

The unit consists of a rocket-like tube 26 feet long and about 4 inches in diameter, containing a gamma-ray-emitting cesium-137 source, a lead shield, and a radiation detector. The device is lowered over the side of a ship and allowed to penetrate the sediment. Once in place, the gamma ray source, shield, and detector move together up and down, inside the probe, for a distance of 11 feet, stopping every 24 inches for 4 minutes to take a measurement. Gamma rays are absorbed in any material through which they pass, according to its density. A low radiation count at the detector indicates a high-density sediment: More radiation is absorbed and less is reflected back to the detector. Conversely, a high count indicates low density. Data are recorded on special cold-resistant film. A number of different sediment measurements can be made in several locations before the unit must be returned to the surface.

OXYGEN ANALYZER The amount of dissolved oxygen in any part of the ocean is a basic quantity that must be determined before some kinds of research can be undertaken. For example, oxygen concentration is important in determining the life-support capability of seawater and in measuring deep-water mixing. In the past this measurement has had to be determined by laborious chemical methods that may subject the water sample to contamination by exposure to atmospheric oxygen. Under an AEC contract, the Research Triangle Institute has developed a dissolved oxygen analyzer that relies on the quantitative oxidation by dissolved oxygen of thallium metal containing a known ratio of radioactive thallium-204.

The seawater sample passes through a column lined with thallium. The thallium is oxydized and goes into solution. It then passes between two facing pancake-shaped radiation counters that record the level of beta radiation from the thallium-204. Since the rate of oxidation, and therefore the rate of release of the thallium to solution, is proportional to the amount of dissolved oxygen in the water, it is simple to calibrate the device to show oxygen content. The system is sensitive enough to detect one part of oxygen in 10 billion of water. And, the device can be towed and take readings at depths of up to one mile, an added advantage that obviates the chances of surface-air contamination.

NEUTRON ACTIVATION ANALYSIS Nuclear energy is contributing to the more accurate and more rapid analysis of minerals in the sea in at least two different ways. The first employs neutron activation analysis, which we have already mentioned. This method is valuable not only in analyzing sediments cored from the ocean floor, but also in the detection and quantitative analysis of trace elements in the water. Knowledge of the role of all natural constituents in the ocean is essential to an understanding of the complex interrelationships of the ocean environment, as we have seen. Identification of trace elements also is a necessary preliminary to determining the effects of purposely introduced radionuclides. Collection of the minute quantities of trace elements is very difficult at best. Once they have been collected and concentrated, neutron activation analysis provides a means for their identification and measurement.

X-RAY FLUORESCENCE is another technique, used to identify the mineral content of ore or sediment. This system was developed (for the purpose of spotting gold being smuggled through Customs) by Tracerlab Division of Laboratory for Electronics, Inc. (LFE), under an AEC contract. Similar equipment was developed simultaneously in England for use by prospectors, geologists and mining engineers. It now may be used at sea in analyzing samples from the sea floor. As is often the case with isotope-based devices, its operation is really quite simple. When excited by radiation from an isotope (or any other radiation source), each element produces its own unique pattern of X-ray fluorescence, that is, it radiates characteristic X rays. By varying filters and measuring the count rate, oceanographers can detect and measure materials, such as tin, copper, lead, and zinc. The British unit is completely transistorized, battery powered, and weighs only 16.5 pounds.

RHODAMINE-B DYE The AEC also has improved oceanographic research in ways that do not involve the use of nuclear energy. Some years ago under the joint sponsorship of the AEC Division of Reactor Development and Technology and the Division of Biology and Medicine, the Waterlift Division of Cleveland Pneumatic Tool Company developed instrumentation and techniques for detecting the presence of the red dye, rhodamine-B, in concentrations as low as one-tenth part per billion. This method is now widely used both for groundwater studies and in the study of currents, diffusion, and pollution in rivers, lakes, and the ocean. In many cases, rhodamine-B is a better tracer in water than radioisotopes, due to the greater ease with which it is detected.

Environmental Safety Studies